Lifting equipment

ABSTRACT

Lifting equipment having a boom structure which includes an outer boom, an inner boom mounted for telescoping movement within the outer boom and an arm, one end of which is pivotally connected to the rearward end of the outer boom to permit movement of the outer end of the boom structure about a substantially horizontal axis and the other end of which is pivotally mounted upon a support structure to permit movement of the first named end of the arm about a substantially horizontal axis.

I United States Patent [151 3,637,044 Eitel 51 Jan. 25, 1972 4] LlF TING EQUIPMENT References Cited [72] inventor: Jay M. Eitel, Atherton, Calif. UNITED STATES PATENTS 2,786,723 3/1957 Harsch ..I82/2 [73] Assignee: General Cable Corporation 3,252,542 5/1966 Thornton-Trump 182/2 22 F] d: 26, 1970 Primary ExaminerKenneth Downey l l 8 June Atlorney-Flehr, Hohback, Test, Albritton & Herbert [21] Appl. No.: 56,071 ABSTRACT Lifting equipment having a boom structure which includes an Related Dam outer boom, an inner boom mounted for telescoping move [63] Continuation of Ser. No. 751,890, Aug. [2, I968, ment within the outer boom and an arm, one end of which is pivotally connected to the rearward end of the outer boom to permit movement of the outer end of the boom structure 52 us. Cl ..l82/l41 about a substantially horizontal axis and the other end of 51] Int. Cl ..E04g 1/18 which is pivolally mounted "P a pp Structure to Permit 58 Field of Search l 82/2, 65, 141 movement of the first named end of the arm about a Substantially horizontal axis.

11 Claims, 3 Drawing Figures PATENTEDJANZSIQTZ 3531044 sum 1 or 2 INVENTOR. Jay .M. E ire! Attorneys LIFTING EQUIPMENT RELATED APPLICATIONS BACKGROUND OF THE INVENTION Heretofore there has been provided means for extending the reach of telescoping booms and articulated booms. Typically for an articulated boom, this has consisted of adding an additional arm to the outer end of the articulated boom structure. For telescoping booms, elevators have been provided for raising the entire telescoping boom structure including the means for rotating the telescoping boom structure. All of these arrangements have disadvantages. Mainly, they are unduly complicated and expensive. In addition, many of them are objectionable because the center of gravity is raised and, therefore, decreases the stability of the apparatus. There is, therefore, a need for a new and improved lifting equipment which overcomes these disadvantages.

SUMMARY OF THE INVENTION AND OBJECTS The lifting equipment consists of a platform and a support structure. Means is provided for rotatably mounting the sup port structure upon the platform for rotation about a vertical axis. Drive means is mounted upon the platform and the support structure for causing rotation of the support structure about the vertical axis. A boom structure is provided which includes an outer boom, an inner boom mounted for telescoping movement within the outer boom and an arm. Means is provided for pivotally connecting one end of the arm to the rearward end of the outer boom for movement of the outer end of the boom structure about a substantially horizontal axis and for pivotally connecting the other end of the arm on the support structure for movement of the first named end of the arm about a horizontal axis. Means is provided for moving the outer boom and the arm about the horizontal axes.

In general, it is an object of the present invention to provide a lifting equipment which includes means for extending the reach of a telescoping boom structure.

Another object of the invention is to provide a lifting equip ment of the above character in which one end of an arm is pivotally connected to the outer boom of the telescoping boom assembly for movement of the outer end of the boom structure about a horizontal axis and the other end of the arm is pivotally connected to a support structure for movement of the first named end of the arm about a substantially horizontal axis.

Another object of the invention is to provide a lifting equipment of the above character in which means is provided for raising the outer boom and the arm about horizontal axes.

Another object of the invention is to provide a lifting equipment of the above character in which the movement of the outer boom and the arm occur simultaneously.

Another object of the invention is to provide a lifting equipment of the above character in which the movement of the outer boom and the arm can be independent of each other.

Another object of the invention is to provide a lifting equipment of the above character in which the center of gravity is not changed appreciably as the boom structure is raised and lowered.

Additional objects and features of the invention will appear from the following description in which the preferred embodiments are set forth in detail in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side elevational view ofa lifting equipment incorporating the present invention.

FIG. 2 is a partial plan view of the lifting equipment shown in FIG. 1.

FIG. 3 is an enlarged detail view showing the means provided for raising and lowering the outer boom and the arm pivotally connected to the outer boom.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The lifting equipment shown in the drawings consists of a self-propelled vehicle 11 having front and rear wheels 12 and 13 rotatably mounted upon a chassis or frame 14 which serves as a platform. Simple motive means (not shown) is provided for supplying power to the rear wheels of the vehicle. A van type body 16 is mounted on the chassis 14. The body 16 is formed to provide a driving station for the self-propelled vehicle and is provided with a front windshield 18 for the driver of the vehicle. The body 16 is provided with a side entrance door 19 whereby the operator may enter the driving station in the vehicle. As can be seen from FIG. 1, the body 16 extends to the rear to provide a vanlike enclosure. The front end of the body 14 is provided with a rectangular space (not shown) which is adapted to receive a workmans basket 21 as hereinafter described so that it is positioned alongside the driving station whereby the driver may readily enter and leave the workmans basket with respect to the driving station without dismounting from the vehicle. This space is preferably accessible from the driving station either by a door (not shown) provided in the body or by an opening in the body to permit ingress and egress with respect to the workmans basket 21.

A lifting apparatus 26 is mounted on the self-propelled vehicle 11. The lifting apparatus 26 consists of a support structure 27. The support structure 27 consists of four frame members 28 which are fastened together by suitable means, such as welding, to provide an inverted pyramid in conformation and which is rotatably mounted upon the framework 14 by a hearing structure 29. The support structure 27 also includes a large circular flat plate 31 which is secured to the upper extremities of the frame members 28 by suitable means, such as welding. The plate 31 is provided with an annular down-turned edge portion or lip 31a.

A pair of drive rollers 34 are rotatably mounted upon the plate 31 and are driven by a drive assembly 36 which includes an electric motor and a self-locking worm gear unit for speed reduction (neither of which is shown in detail). The drive assembly 36 is mounted upon the support structure 27 and drives the rollers 34 for rotation of the support structure as hereinafter described. Additional rollers 38 are provided which are also rotatably mounted upon the plate 31. The drive rollers 34 and the rollers 38 engage a circular track structure 41 which is provided with an interior circular, substantially vertical drive surface 42 which is engaged by the rollers 34 and 38. The drive rollers 34, the drive assembly 36 and the rollers 38 and their operation in engaging the circular structure 41 is very similar to that described in conjunction with a number of embodiments in copending U.S. application Ser. No. 697,887, filed Jan. 15, 1968, now U.S. Pat. No. 3,437,175 and, therefore, the detailed construction of the drive means will not be disclosed. As pointed out therein, such drive means generally includes at least three rollers for engaging the circular track in which at least one of the rollers is driven to provide relative motion between the support structure and the circular track structure.

The circular track structure 41 is mounted upon a framework 44 which includes a plurality of members 46 which are secured to the circular track structure by suitable means, such as welding, and are also mounted in a fixed position upon the chassis or frame 14 of the vehicle 11 so that the framework 44 provides means for rigidly securing the circular track structure 41 to the frame 14.

A boom structure 51 is mounted upon the large plate 31 of the support structure 27. The boom structure 51 consists of an outer boom 52, an inner or telescoping boom 53 and a pair of arms 54. Telescoping movement of the inner boom with respect to the outer boom 52 can be accomplished in a number of ways such as that shown in U.S. Pat No. 2,896,750, or that described in copending application Ser. No. 697,900, filed Jan. 15, 1968 now US. Pat. No. 3,480,109. The extension and retraction of the inner boom 53 with respect to the outer boom 52 is accomplished by a spur gear drive assembly 56 which includes an electric motor 57, both of which are mounted upon the outer boom 52. The workmans basket 21 is pivotally mounted on the outer end of the inner boom 53 and is provided with a control assembly 58 such as that described in U.S. Pat. No. 2,841,659 to permit control of the boom structure 51 as hereinafter described.

Means is provided for pivotally mounting one end of each of the arms 54 to the rearward end of the outer boom 52 and consists of side plates 50 which are secured to the rear end of the outer boom 52 by suitable means such as welding, and which have their rearward extremities outwardly flared and which carry aligned pivot pins 59 that lie in a horizontal plane. The ends of the arms 54 which are pivotally connected to the outer boom 52 are pivotally mounted upon the pivot pins 59 so that the outer end of the boom structure 51 can be pivoted about a substantially horizontal axis. The other ends of the arms 54 are pivotally connected to aligned pivot pins 61 which lie in a horizontal plane and which are mounted upon the forward extremities of large, vertically disposed, spaced parallel support plates 62 mounted in fixed positions upon the plate 31 and which form a part of the support structure 27. Thus, it can be seen that the last-named ends of the arms 54 serve as pivot points for movement of the outer ends of the arms 54 about a substantially horizontal axis.

Power means is provided for causing movement of the outer boom 52 and the arms 54 about the horizontal axes formed by the pivot pins 59 and 61. Such means consists ofa pair of double-acting hydraulic actuators 66 and 67 extending through a centrally disposed opening 64 in plate 31. The hydraulic actuator 66 is provided for raising and lowering the outer boom 52 and the hydraulic actuator 67 is provided for raising and lowering the arms 54. The hydraulic actuator 66 consists ofa cylinder 68 which is pivotally mounted on a pin 69 carried by the support structure 27. The hydraulic actuator 66 also includes a piston (not shown) and a piston rod 71 which is pivotally connected to a pin 72 mounted in ears 73 secured to the outer boom 52. The hydraulic actuator 67 consists of a cylinder 74 which is pivotally mounted upon a pin 76 carried by the support structure 27. The hydraulic actuator 67 also includes a piston (not shown) and a piston rod 77 which is pivotally mounted upon a pin 79 carried by cars 81 mounted upon the spaced arms 54.

Means is provided for supplying hydraulic fluid to the hydraulic actuators 66 and 67 for operation of the same and consists of an elevation drive power pack 84 which consists of an electric motor 86, a pump (not shown) and a storage tank 87. The power pack 84 is mounted upon the cylinder 74 and moves with the cylinder 74. Piping is provided for connecting the power pack 84 to the hydraulic actuators 66 and 67 and consists of an output line 88 which is connected from the output of the power pack to the lower extremity of the cylinder 74. A line 89 connects the upper end of the cylinder 74 to the lower end of the cylinder 68. A line 91 connects the upper end of the cylinder 68 to the return inlet of the elevation power pack 84. The hydraulic system which is provided also includes certain check valves and the like which are well known to those skilled in the art and are, therefore, not shown.

With the arrangement shown and as hereinafter described, it can be seen that a single power pack 84 is provided for operating both the hydraulic actuators 66 and 67. It, however, should be appreciated that, if desired, an additional power pack 96 shown in dotted lines in FIG. 3 could be provided for the hydraulic actuator 66 so that each of the hydraulic actua' tors 66 and 67 would have its own power pack and thus one could be operated independently of the other. With such an arrangement, it is readily apparent that the output and the input for each power pack would be connected to the ends of the associated cylinder and for that reason a power pack would only operate the cylinder on which it is mounted.

A boom rest 98 is mounted on the body 16 for supporting the outer end of the outer boom 52 when the boom structure 51 is in a stowed position.

Operation of the lifting equipment may now be briefly described as follows. Let it be assumed that a single power pack such as that shown in FIG. 3 mounted upon the hydraulic actuator 66 has been provided. Also, let it be assumed that the lifting equipment is in the storage position shown in solid'lines in FIG. 1 and that the operator of the equipment wishes to perform work such as changing street lights. The operator would drive the vehicle to the desired location and then would step from the driving station within the vehicle and enter the work-,

mans basket 21 alongside the driving station without dismounting from the vehicle. The operator would then engage the control mechanism 58 which, through conventional control circuitry, would cause operation of any one or all of the three drive assemblies provided, that is, the drive assembly 36 for causing rotation of the boom structure about a substantially vertical axis, the spur gear drive assembly 56 for causing extension and retraction of the inner boom 53, and the elevation power pack 84 for raising and lowering the outer boom 52 and the arms 54.

Thus, initially, the operator would operate the control mechanism 58 to operate the elevation power pack 84 to raise the boom structure and to elevate the workman s basket out of the position alongside the driving station. As soon as the elevation power pack 84 is placed in operation, hydraulic fluid is supplied to the cylinder 74 which causes the piston therein to be moved upwardly to raise the arms 54. At the same time, fluid is being discharged from the cylinder 74 and is being forced into the cylinder 68 to raise the piston therein to simultaneously cause a raising of the outer boom with respect to the horizontal axis formed by the pins 59. It can be readily seen that by sizing of the cylinders 74 and 68 that desired movement can be obtained between the piston in the cylinder 68 and the piston in the cylinder 74. It is only necessary that the volume of the cylinders 68 and 74 should be substantially the same. Thus, it can be seen that by increasing the diameter of the cylinder 74, it is possible to provide the same volume within the cylinder 74 as cylinder 68 although it is substantially shorter in length than the cylinder 68. With both the cylinders 68 and 74 of the same capacity, it can be seen that at the time that the piston arrives at the top of the cylinder 74, the piston in the cylinder 68 also would arrive at the top of the cylinder 68. It can be seen that the sizing of the cylinders 74 and 68 is such that the stroke for the piston in the cylinder 74 is substantially less than the cylinder 68. This is necessary because, as can be seen in FIG. 1, the stroke of the hydraulic actuator 66 must accommodate the stroke of the hydraulic actuator 67 in order to make it possible to raise the outer boom relative to the horizontal axis 59 carried by the arms 54.

From the foregoing description, it can be seen that upon operation of the control mechanism 58, both the arms 54 and the outer boom 52 are raised simultaneously about the horizontal axes formed by the pivot pins 59 and 61.

After the workmans basket 58 has cleared the body 16, the boom structure can be rotated about a horizontal axis by operation of the rotation drive assembly 36. In addition, the inner boom can be extended and retracted by operation of the spur gear drive unit 56, all controllable from the control mechanism 58.

After the operator has completed the work he had intended to do aloft, the operator can again lower himself into a position alongside the, driving station by operating the control mechanism to properly position the boom structure so that it is ready to be loaded into the space alongside the driving station by operation of the elevation power pack 84. This permits the fluid to flow from the double-acting hydraulic actuators 66 and 67 in an opposite direction and to permit lowering of the pistons within the hydraulic actuators 66 and 67 until the outer extremity of the outer boom comes into engagement with the boom rest 98. The operator can then step from the workmans basket into the driving station and can then move the vehicle to the next location at which work is to be performed.

In the event it is desired to control the operation of the hydraulic actuators 66 and 67 independent of each other, the other elevation power pack 96 is provided as hereinafter described and controls are provided which are operable with the control mechanism 58 to operate the hydraulic actuators 66 or 67 independently of each other or simultaneously. Alternatively, in place of or in addition to the control mechanism 58, a pair of switches can be provided in the workmans basket 21 to permit control of the power packs 84 and 96. With independent operation of the actuators 66 and 67, the operation is very similar. Generally, it would be desirable to first elevate the boom by utilizing the hydraulic actuator 66 and thereafter if additional height is required, the hydraulic actuator 67 could be operated to raise the arms 54. In lowering, the arms 54 would preferably be lowered first and the outer boom 52 could be lowered.

With the lifting equipment herein described, it can be seen that the arms 54 with the hydraulic actuator 67 which is provided for raising and lowering the same provides means whereby the elevation to which the workman BASKET 2] CAN BE RAIsED CAN BE EXTENDED SIGNIFICANTLY. FoR EXAMPLE, IT WOULD BE POSSIBLE TO INCREASE THE REACH or A TYPICAL Lil-TING EQUIPMENT FROM 4 to ft. by the use of such arms. The present lifting equipment also has the distinct advantage in that it makes it possible to attain increased vertical height while still retaining a relatively compact boom structure which, as can be seen from FIG. 1, is generally within the confines of the body 16 and does not extend beyond the body 16 when it is in the stowed-away or lowered position. The design of the lifting equipment is also such that as the boom structure is raised and lowered, the center of gravity for the lifting equipment is raised very little and, for that reason, the stability of the lifting equipment is not significantly decreased by use of the arms 54 for obtaining the increased height. This is true because most of the mass of the lifting equipment does not change its vertical position with respect to the wheels 12 and 13 of the vehicle. For example, all of the means which is provided for causing relative rotational movement between the support structure 27 and the track structure 41 remains in a generally fixed vertical position. It is only the boom structure itself which is raised and lowered which is relatively light in weight and does not significantly change the center of gravity for the lifting equipment as it is raised and lowered.

It also can be seen that the arrangement of the arms 54 relative to the outer boom 52 and the inner boom 53 is such that the horizontal reach of the boom structure is automatically controlled when both of the hydraulic actuators 66 and 67 are operated simultaneously for elevating of the boom structure. This is true because as the arms 54 are elevated, the outer boom 52 is also elevated so that the horizontal reach is not increased significantly. Even if the hydraulic actuators 66 and 67 are independently controlled, it can be readily seen that the lifting equipment can be operated so that the horizontal reach is not extended significantly by first elevating the outer boom structure and then elevating the arms 54, Thus, it can be seen that the stability of the lifting equipment during operation is not significantly decreased by the addition of the arms 54 for obtaining increased vertical reach for the lifting equipment.

Iclaim:

1. In a lifting equipment, a mobile platform, a support structure, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure for causing rotation of the support structure about a substantially vertical axis, a boom structure, said boom structure including an outer boom and an inner boom mounted for telescoping movement withing the outer boom, said support structure including a plate, a pair of spaced members mounted on Said plate, a pair of arms, means pivotally mounting said arms on said spaced members to permit the movement of the arms about a substantially horizontal axis, means pivotally connecting the outer boom to said arms to permit the movement of the outer boom about a substantially horizontal axis, and means for moving the outer boom and the arms about said substantially horizontal axes, said spaced members, said arms,

and said outer boom being arranged in such a manner so that when the lifting equipment is in a storage position the outer boom structure is disposed between the arms and the spaced members and the boom structure, the arms and the spaced members lie in generally the same plane.

2. A lifting equipment as in claim 1 wherein said spaced members and said arms are constructed so that when the lifting equipment is in a storage position, the arms do not extend substantially beyond the platform.

3. In a lifting equipment, a platform, a support structure, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure and causing rotation of the support structure about a substantially vertical axis, a boom structure, said boom structure including an outer boom, an inner boom mounted for telescoping movement withing the outer boom, said support structure including a generally horizontal plate and a pair of spaced parallel substantially vertical members mounted on said plate, arms means, said arm means including a pair of arms, means for pivotally connecting one end of each of the arms of said arm means to the rearward end of the outer boom to permit movement of the outer end of the boom structure about a substantially horizontal axis, means for pivotally connecting the other end of each of the arms of said arm means to said vertical members to permit movement of the first named ends of the arm means about a substantially horizontal axis and means mounted upon the support structure for moving the outer boom and the arm means about their substantially horizontal axes.

4. A lifting equipment as in claim 3 wherein said arms are pivotally mounted on the forward extremities of the vertical members so that when the lifting equipment is in a storage position, the arms do not extend substantially beyond the platform.

5. In a lifting equipment, a platform, a support structure, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure and causing rotation of the support structure about said substantially vertical axis, a boom structure, said boom structure including an outer boom and an inner boom mounted for telescoping movement within the outer boom, arm means, means for pivotally connecting one end of the arm means to the rearward end of the outer boom to permit movement of the outer end of the boom structure. about a substantially horizontal axis and for pivotally connecting the other end of the arm means on the support structure to permit movement of the first named end of the arm means about a horizontal axis, and means mounted upon the support structure for moving the outer boom and the am means about their substantially horizontal axes whereby he inner boom can be raised and lowered either by movement of the outer boom or by movement of the arm means.

6. A lifting equipment as in claim 5 wherein said means for moving the outer boom and the arm means about the horizontal axes includes means for moving the outer boom and the arm means simultaneously.

7. A lifting equipment as in claim 5 wherein said means for moving the outer boom and the arm means about the horizontal axes includes means for moving the arm means and the outer booms independently of each other.

8. A lifting equipment as in claim 5 wherein said means for moving the outer boom and the arm means about the horizontal axes includes a pair of hydraulic actuators mounted on the support structure, one of which is substantially longer than the other with the longer one being connected to said outer boom and the other one being connected to the arm means and means interconnecting the hydraulic actuators so that when fluid is supplied to one of the actuators, fluid is also applied to the other of the actuators to operate both of them simultaneously.

9. In a lifting equipment, a platform, a support structure, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure and causing rotation of the support structure about a substantially vertical axis, a boom structure, said boom structure including an outer boom, an inner boom mounted for telescoping movement within the outer boom, means for extending and retracting the inner boom with respect to the outer boom, height extension means mounted on the support structure adjacent the upper end thereof and rotatable with the support structure, means pivotally mounting said outer boom on the height extension means to permit pivotal movement of the boom structure about a substantially horizontal axis, means mounted on the support structure and connected to the boom structure for causing pivotal movement of the boom structure about said substantially horizontal axis to thereby cause raising and lowering of the outer end of the inner boom and extensible means mounted on the support structure and connected to the height extension means for raising and lowering the height extension means with respect to the support structure.

10. A lifting equipment as in claim 9 wherein said means mounted on the support structure and connected to the boom structure consists of a hydraulic actuator having one end connected to the support structure and having the other end connected to the boom structure and wherein said extensible means for raising and lowering the height extension means includes an additional hydraulic actuator having one end connected to the support structure and having the other end connected to the height extension means together with a workmans platform carried on the outer end of the inner boom, control means accessible to the operator on the workman's platform for causing operation of the rotation means and actuation of said hydraulic actuators.

11. in a lifting equipment, a wheeled vehicle having a platform, a vanlike body mounted on the platform and having a roof, a support structure mounted within the vanlike body and having its upper surface generally flush with the roof of the vanlike body, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure and causing rotation of the support structure about said substantially vertical axis, a boom structure, said boom structure including an outer boom, an inner boom mounted for telescoping movement within the outer boom, means for extending and retracting the inner boom with respect to the outer boom, height extension means mounted on the upper end of the support structure and extending above the roof of the vanlike body for rotational movement with the support structure, means pivotally mounting said outer boom on the height extension means to permit pivotal movement of the boom structure about a substantially horizontal axis, means mounted on the support structure and connected to the boom structure for causing pivotal movement of the boom structure about said substantially horizontal axis to thereby cause raising and lowering of the outer end of the inner boom and extensible means mounted on the support structure and connected to the height extension means for raising and lowering the height extension means relative to the support structure. 

1. In a lifting equipment, a mobile platform, a support structure, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure for causing rotation of the support structure about a substantially vertical axis, a boom structure, said boom structure including an outer boom and an inner boom mounted for telescoping movement withing the outer boom, said support structure including a plate, a pair of spaced members mounted on said plate, a pair of arms, means pivotally mounting said arms on said spaced members to permit the movement of the arms about a substantially horizontal axis, means pivotally connecting the outer boom to said arms to permit the movement of the outer boom about a substantially horizontal axis, and means for moving the outer boom and the arms about said substantially horizontal axes, said spaced members, said arms, and said outer boom being arranged in such a manner so that when the lifting equipment is in a storage position the outer boom structure is disposed between the arms and the spaced members and the boom structure, the arms and the spaced members lie in generally the same plane.
 2. A lifting equipment as in claim 1 wherein said spaced members and said arms are constructed so that when the lifting equipment is in a storage position, the arms do not extend substantially beyond the platform.
 3. In a lifting equipment, a platform, a support structure, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure and causing rotation of the support structure about a substantially vertical axis, a boom structure, said boom structure including an outer boom, an inner boom mounted for telescoping movement withing the outer boom, said support structure including a generally horizontal plate and a pair of spaced parallel substantially vertical members mounted on said plate, arms means, said arm means including a pair of arms, means for pivotally connecting one end of each of the arms of said arm means to the rearward end of the outer boom to permit movement of the outer end of the boom structure about a substantially horizontal axis, means for pivotally connecting the other end of each of the arms of said arm means to said vertical members to permit movement of the first named ends of the arm means about a substantially horizontal axis and means mounted upon the support structure for moving the outer boom and the arm means about their substantially horizontal axes.
 4. A lifting equipment as in claim 3 wherein said arms are pivotally mounted on the forward extremities of the vertical members so that when the lifting equipment is in a storage position, the arms do not extend substantially beyond the platform.
 5. In a lifting equipment, a platform, a support structure, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure and causing rotation of the support structure about said substantially vertical axis, a boom structure, said boom structure including an outer boom and an inner boom mounted for telescoping movement within the outer boom, arm means, means for pivotally connecting one end of the arm means to the rearward end of the outer boom to permit movement of the outer end of the boom structure about a substantially horizontal axis and for pivotally connecting the other end of the arm means on the support structure to permit movement of the first named end of the arm means about a horizontal axis, and means mounted upon the support structure for moving the outer boom and the arm means about their substantially horizontal axes whereby the inner boom can be raised and lowered either by movement of the outer boom or by movement of the arm means.
 6. A lifting equipment as in claim 5 wherein said means for moving the outer boom and the arm means about the horizontal axes includes means for moving the outer boom and the arm means simultaneously.
 7. A lifting equipment as in claim 5 wherein said means for moving the outer boom and the arm means about the horizontal axes includes means for moving the arm means and the outer booms independently of each other.
 8. A lifting equipment as in claim 5 wherein said means for moving the outer boom and the arm means about the horizontal axes includes a pair of hydraulic actuators mounted on the support structure, one of which is substantially longer than the other with the longer one being connected to said outer boom and the other one being connected to the arm means and means interconnecting the hydraulic actuators so that when fluid is supplied to one of the actuators, fluid is also applied to the other of the actuators to operate both of them simultaneously.
 9. In a lifting equipment, a platform, a support structure, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure and causing rotation of the support structure about a substantially vertical axis, a boom structure, said boom structure including an outer boom, an inner boom mounted for telescoping movement within the outer boom, means for extending and retracting the inner boom with respect to the outer boom, height extension means mounted on the support structure adjacent the upper end thereof and rotatable with the support structure, means pivotally mounting said outer boom on the height extension means to permit pivotal movement of the boom structure about a substantially horizontal axis, means mounted on the support structure and connected to the boom structure for causing pivotal movement of the boom structure about said substantially horizontal axis to thereby cause raising and lowering of the outer end of the inner boom and extensible means mounted on the support structure and connected to the height extension means for raising and lowering the height extension means with respect to the support structure.
 10. A lifting equipment as in claim 9 wherein said means mounted on the support structure and connected to the boom structure consists of a hydraulic actuator having one end connected to the support structure and having the other end connected to the boom structure and wherein said extensible means for raising and lowering the height extension means includes an additional hydraulic actuator having one end connected to the support structure and having the other end connected to the height extension means together with a workman''s platform carried on the outer end of the inner boom, control means accessible to the operator on the workman''s platform for causing operation of the rotation means and actuation of said hydraulic actuators.
 11. In a lifting equipment, a wheeled vehicle having a platform, a Vanlike body mounted on the platform and having a roof, a support structure mounted within the vanlike body and having its upper surface generally flush with the roof of the vanlike body, means for rotatably mounting the support structure upon the platform for rotation about a substantially vertical axis, drive means carried by the platform and the support structure and causing rotation of the support structure about said substantially vertical axis, a boom structure, said boom structure including an outer boom, an inner boom mounted for telescoping movement within the outer boom, means for extending and retracting the inner boom with respect to the outer boom, height extension means mounted on the upper end of the support structure and extending above the roof of the vanlike body for rotational movement with the support structure, means pivotally mounting said outer boom on the height extension means to permit pivotal movement of the boom structure about a substantially horizontal axis, means mounted on the support structure and connected to the boom structure for causing pivotal movement of the boom structure about said substantially horizontal axis to thereby cause raising and lowering of the outer end of the inner boom and extensible means mounted on the support structure and connected to the height extension means for raising and lowering the height extension means relative to the support structure. 